The present invention relates to a filter/drier assembly for trapping foreign particles and removing moisture from refrigerant circulated in a vapor-liquid phase refrigeration system. Devices of this type are commonly employed in motor vehicle passenger compartment air conditioning systems to maintain the efficiency of the heat transfer capability of the refrigerant and to prevent moisture and foreign particles from entering the refrigerant compressor and reducing the service life of the compressor.
A commonly employed filter/drier for automotive air conditioning system installations is shown in FIG. 1 and has an inlet fitting 1 attached to a cup-shaped housing shell 2 which has disposed therein a louvered baffle plate 3 which forms a plenum 4 adjacent the inlet fitting. A layer of fibrous filter material 5 is disposed adjacent the baffle plate 3.
The central region of the shell 2 is filled with desiccant material 6 covered by a second filter layer 7 and retained in the shell by a second louvered baffle plate 8. The shell is closed by a cap 9 secured to the shell by weldment. An outlet fitting 10 is attached to the cap 9 typically by weldment. The prior art device of FIG. 1 is thus a flow-through type filter/drier intended for in-line installation in a refrigeration system. The prior art filter/drier of FIG. 1 has the disadvantage that it is difficult to assemble by virtue of the requirement to install the two baffles in the shell for retaining the desiccant and the attachment of separate fittings to the relatively thin shell and cap. In particular, it has proven difficult to provide a fluid pressure tight seal of the weldment of the cap to the shell in view of the thinness of the shell and cap material for the desired lightweight construction. It has thus been desired to provide an improved filter/drier for a refrigerant system which is easy to assemble, light in weight, with a reduced number of components and joining operations and is low in manufacturing cost.